Elevated global cerebral blood flow, oxygen extraction fraction and unchanged metabolic rate of oxygen in young adults with end-stage renal disease: an MRI study

Objectives: To noninvasively assess global cerebral blood flow (CBF), oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO₂) in young adults with end-stage renal disease (ESRD). Methods: Thirty-six patients and 38 healthy volunteers were included and took part in MR examinations, blood and neuropsychological tests. CBF and OEF were measured by phase-contrast and T2-relaxation-under-spin-tagging MRI techniques, respectively. CMRO₂ was computed from CBF, OEF and hematocrit according to Fick’s principle. Correlations were performed between MR measurements, blood biochemistry measurements and neuropsychological test scores. Results: Compared with controls, ESRD patients had elevated CBF (72.9 ± 12.5 vs. 63.8 ± 8.5 ml min⁻¹ 100 g⁻¹, P < 0.001), elevated OEF (47.2 ± 10.2 vs. 35.8 ± 5.4 %, P < 0.001), but unaffected CMRO₂ (199.5 ± 36.4 vs. 193.8 ± 28.6 μmol O₂ min⁻¹ 100 g⁻¹, P = 0.879). Hematocrit negatively correlated with CBF (r = −0.640, P < 0.001) and OEF (r = −0.701, P < 0.001), but not with CMRO₂. Altered neuropsychological test scores of ESRD patients were associated with OEF and CBF, but not with CMRO₂. There were weak relationships between eGFR and hematocrit (r = 0.308, P = 0.068) or CBF (r = 0.318, P = 0.059). Conclusion: Our findings suggested that anaemic young adults with ESRD may afford higher CBF and OEF to maintain a normal CMRO₂. Despite this compensatory process, however, cognitive function was still impaired and its severity was correlated with their CBF and OEF abnormality. Key Points: • Anaemic young adults with ESRD may afford higher CBF and OEF. • Anaemic young adults with ESRD maintain a normal CMRO₂. • Cognitive function was still impaired in young ESRD adults. • The severity of cognitive dysfunction correlated with CBF and OEF changes.